二、反转链表

题目描述

Reverse a linked list from position m to n. Do it in-place and in one-pass.For example:Given1->2->3->4->5->NULL, m = 2 and n = 4,return1->4->3->2->5->NULL.Note:Given m, n satisfy the following condition:1 ≤ m ≤ n ≤ length of list.

三、深搜

题目描述

Given a collection of integers that might contain duplicates, S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must not contain duplicate subsets.